What is GERD? Acid reflux explained in plain English

Gastro-oesophageal reflux disease, known as GERD in the US and GORD in the UK, is what doctors call acid reflux when it happens often enough, or badly enough, to cause troublesome symptoms or damage. It is one of the most common digestive conditions in the world, and for most people it is very manageable.

What happens in your body

When you swallow, food travels down the oesophagus (the food pipe) into the stomach. At the bottom of the oesophagus is a ring of muscle called the lower oesophageal sphincter (LOS). It opens to let food through, then closes again to keep stomach contents where they belong. The diaphragm, the sheet of muscle under your lungs, wraps around this point and adds to the seal.

Reflux happens when this barrier relaxes at the wrong moment or does not close properly. Stomach acid, and sometimes food, pepsin or bile, flows back up into the oesophagus. The stomach has a thick protective lining, but the oesophagus does not, so the acid irritates it. That irritation is the burning feeling known as heartburn.

Almost everyone has small reflux episodes every day, usually without noticing. Swallowing and saliva wash the acid back down within seconds. Reflux becomes a disease when it happens often, lasts longer, or causes trouble.

Reflux, heartburn and GERD: what is the difference?

• Acid reflux is the event itself: stomach contents moving up into the oesophagus.
• Heartburn is the most common symptom: a burning feeling behind the breastbone, often after eating or when lying down. It has nothing to do with the heart.
• GERD is the condition. Doctors generally use the term when reflux symptoms are troublesome, happen regularly (often twice a week or more), or when reflux has damaged the oesophagus.

Occasional heartburn after a big meal is normal. If you are reaching for antacids several times a week, or symptoms are affecting your sleep or meals, it is worth speaking to a doctor or pharmacist.

How common is it?

A large analysis of studies from around the world found that roughly 13% of adults have reflux symptoms at least once a week. Rates are higher in North America, Europe and the Middle East than in East Asia, and higher in people who are older, carry extra weight, or smoke. GERD and GORD are the same condition; the spelling depends on whether you write "esophagus" (US) or "oesophagus" (UK). See GERD vs GORD.

Why the barrier stops working well

There is usually no single cause. Common contributors include:

• Extra weight around the abdomen, which raises the pressure on the stomach.
• A hiatus hernia, where the top of the stomach slides up through the diaphragm and weakens the seal. See hiatus hernia.
• Pregnancy, through hormones that relax the LOS and the growing baby pressing on the stomach.
• Smoking, which weakens the LOS and reduces saliva, the body's natural acid neutraliser.
• Large or late meals, which fill the stomach shortly before you lie down.
• Some medicines, such as certain blood pressure tablets, anti-inflammatory painkillers and some antidepressants.

Read more in symptoms and causes.

Is GERD dangerous?

For most people GERD is a nuisance rather than a danger, and it responds well to lifestyle changes and medicine. Years of uncontrolled acid exposure can inflame the oesophagus and, in a minority of people, lead to complications such as narrowing or Barrett's oesophagus. That is why some symptoms, like difficulty swallowing or weight loss, always need a doctor. See complications and when to see a doctor.

What helps

Treatment usually follows a step-by-step path:

1. Lifestyle and diet: smaller meals, not eating late, raising the head of the bed, losing weight if needed, and avoiding your personal trigger foods. See lifestyle changes and the diet guide.
2. Over-the-counter remedies: antacids and alginates for occasional symptoms.
3. Acid-reducing medicine: H2 blockers and proton pump inhibitors (PPIs), usually as a trial of several weeks.
4. Specialist options: tests and, for a small group, surgery or an endoscopic procedure.

The medications guide explains each step. To find your own patterns, try the free symptom diary and the food trigger checker.